"We will go to Spain in August. (future)"
You should not use "will" when describing plans ->
"We're going to Spain..."
"We're going to go to Spain..."
Additionally, I would say that the tenses you are assigning are too simplistic
Sylvia is writing an e-mail to her brother. (present) -> Actually Present Continuous
Jim has been working since eight o'clock. (present) -> Actually Present Perfect Continuous, which is a tense that can describe EITHER past or ongoing actions.
We had Pizza last night. (Past) -> Actually Past Simple
I am learning French. (present) -> Actually Present Continuous
This is probably an area where one-to-one comparisons doesn't work, as English uses a number of additional tenses that German does not.